Plymouth is located in Hancock county Illinois with a geographic area of 0.6 square miles. The total population in Plymouth is 441 with 51.5% male and 48.5% female. Children under age 5 represent 7.7% of the population, under age 18 equal 18.6% of the population and over age 65 is 32.2% of the population. The median household income is $47,083, per capita income is $26,386. There are a total of 198 housing units with 74.2% owner occupied. Education includes 57.6% of residents that are high school graduates and 3.5% with a bachelor's degree or higher. The average temperature in Plymouth in the summer is 74 degrees, and in the winter 27 degrees.